Chapter 6B. Fundamental Principles

Section 6B.01 Fundamental
Principles of Temporary Traffic Control

Support:
Whenever the acronym "TTC" is used in this Chapter, it
refers to "temporary traffic control."

Standard:
The needs and control of all road users (motorists, bicyclists,
and pedestrians within the highway, including persons with disabilities
in accordance with the Americans with Disabilities Act of 1990 (ADA),
Title II, Paragraph 35.130) through a TTC zone shall be an essential
part of highway construction, utility work, maintenance operations,
and the management of traffic incidents.

Support:
Construction, maintenance, utility, and incident zones can all benefit
from TTC to compensate for the unexpected or unusual situations
faced by road users. When planning for TTC in these zones, it can
be assumed that it is appropriate for road users to exercise caution.
Even though road users are assumed to be using caution, special
care is still needed in applying TTC techniques.

Special plans preparation and coordination with
transit, other highway agencies, law enforcement and other emergency
units, utilities, schools, and railroad companies might be needed
to reduce unexpected and unusual road user operation situations.

During TTC activities, commercial vehicles might
need to follow a different route from passenger vehicles because
of bridge, weight, clearance, or geometric restrictions. Also, vehicles
carrying hazardous materials might need to follow a different route
from other vehicles. The Hazardous Materials and National Network
signs are included in Sections 2B.52
and 2B.53,
respectively.

Experience has shown that following the fundamental
principles of Part 6 will assist road
users and help protect workers in the vicinity of TTC zones.

Guidance:
Road user and worker safety and accessibility in TTC zones should
be an integral and high-priority element of every project from planning
through design and construction. Similarly, maintenance and utility
work should be planned and conducted with the safety and accessibility
of all motorists, bicyclists, pedestrians (including those with
disabilities), and workers being considered at all times. If the
TTC zone includes a highway-rail grade crossing, early coordination
with the railroad company should take place.

Support:
Formulating specific plans for TTC at traffic incidents is difficult
because of the variety of situations that can arise.

Guidance:
General plans or guidelines should be developed to provide safety
for motorists, bicyclists, pedestrians, workers, enforcement/emergency
officials, and equipment, with the following factors being considered:

The basic safety principles governing the design of permanent
roadways and roadsides should also govern the design of TTC zones.
The goal should be to route road users through such zones using
roadway geometrics, roadside features, and TTC devices as nearly
as possible comparable to those for normal highway situations.

A TTC plan, in detail appropriate to the complexity of the work
project or incident, should be prepared and understood by all
responsible parties before the site is occupied. Any changes in
the TTC plan should be approved by an official knowledgeable (for
example, trained and/or certified) in proper TTC practices.

Road user movement should be inhibited as little
as practical, based on the following considerations:

TTC at work and incident sites should be designed on the assumption
that drivers will only reduce their speeds if they clearly perceive
a need to do so (see Section
6C.01).

Frequent and abrupt changes in geometrics such as lane narrowing,
dropped lanes, or main roadway transitions that require rapid
maneuvers, should be avoided.

Provisions should be made for the reasonably safe operation
of work, particularly on high-speed, high-volume roadways.

Road users should be encouraged to use alternative routes that
do not include TTC zones.

Bicyclists and pedestrians, including those with disabilities,
should be provided with access and reasonably safe passage through
the TTC zone.

Roadway occupancy should be scheduled during off-peak hours
and, if necessary, night work should be considered.

Early coordination with officials having jurisdiction over the
affected cross streets and providing emergency services should
occur before roadway or ramp closings.

Motorists, bicyclists, and pedestrians should
be guided in a clear and positive manner while approaching and traversing
TTC zones and incident sites. The following principles should be
applied:

Adequate warning, delineation, and channelization should be
provided to assist in guiding road users in advance of and through
the TTC zone or incident site by using proper pavement marking,
signing, or other devices that are effective under varying conditions.
Providing information that is in usable formats by pedestrians
with visual disabilities should also be considered.

TTC devices inconsistent with intended travel paths through
TTC zones should be removed or covered. However, in intermediate-term
stationary, short-term, and mobile operations, where visible permanent
devices are inconsistent with intended travel paths, devices that
highlight or emphasize the appropriate path should be used. Providing
traffic control devices that are accessible to and usable by pedestrians
with disabilities should be considered.

To provide acceptable levels of operations, routine
day and night inspections of TTC elements should be performed as
follows:

Individuals who are knowledgeable (for example, trained and/or
certified) in the principles of proper TTC should be assigned
responsibility for safety in TTC zones. The most important duty
of these individuals should be to check that all TTC devices of
the project are reasonably consistent with the TTC plan and are
effective in providing reasonably safe conditions for motorists,
bicyclists, pedestrians, and workers.

As the work progresses, temporary traffic controls and/or working
conditions should be modified in order to provide reasonably safe
and efficient road user movement and to provide worker safety.
The individual responsible for TTC should have the authority to
halt work until applicable or remedial safety measures are taken.

TTC zones should be carefully monitored under varying conditions
of road user volumes, light, and weather to check that applicable
TTC devices are effective, clearly visible, clean, and in compliance
with the TTC plan.

When warranted, an engineering study should be made (in cooperation
with law enforcement officials) of reported crashes occurring
within the TTC zone. Crash records in TTC zones should be monitored
to identify the need for changes in the TTC zone.

Attention should be given to the maintenance of
roadside safety during the life of the TTC zone by applying the
following principles:

Channelization of road users should be accomplished by the use
of pavement markings, signing, and crashworthy, detectable channelizing
devices.

Work equipment, workers' private vehicles, materials, and debris
should be stored in such a manner to reduce the probability of
being impacted by run-off-the-road vehicles.

Each person whose actions affect TTC zone safety,
from the upper-level management through the field workers, should
receive training appropriate to the job decisions each individual
is required to make. Only those individuals who are trained in proper
TTC practices and have a basic understanding of the principles (established
by applicable standards and guidelines, including those of this
Manual) should supervise the selection, placement, and maintenance
of TTC devices used for TTC zones and for incident management.

Good public relations should be maintained by
applying the following principles:

The needs of all road users should be assessed such that appropriate
advance notice is given and clearly defined alternative paths
are provided.

The cooperation of the various news media should be sought in
publicizing the existence of and reasons for TTC zones because
news releases can assist in keeping the road users well informed.

The needs of abutting property owners, residents, and businesses
should be assessed and appropriate accommodations made.

The needs of emergency service providers (law enforcement, fire,
and medical) should be assessed and appropriate coordination and
accommodations made.

The needs of railroads and transit should be assessed and appropriate
coordination and accommodations made.

The needs of operators of commercial vehicles such as buses
and large trucks should be assessed and appropriate accommodations
made.

Standard:
Before any new detour or temporary route is opened to traffic, all
necessary signs shall be in place.

All TTC devices shall be removed as soon as practical
when they are no longer needed. When work is suspended for short
periods of time, TTC devices that are no longer appropriate shall
be removed or covered.